Respiratory Distress and Failure

Disorders of respiration in newborn infants can be categorized as either central nervous system (CNS) failure, representing depression or failure of the respiratory center, or peripheral respiratory difficulty, indicating interference with the alveolar exchange of oxygen and carbon dioxide. Cyanosis occurs in both groups (see Table 92-1). Respiratory problems encountered in the delivery room are most frequently those of airway obstruction and depression of the CNS (maternal medications, asphyxia) with an absence of adequate respiratory effort. Respiratory distress in the presence of good respiratory effort should lead to an immediate consideration of the underlying cause and is an indication for radiographic examination of the chest.

If respiratory movements are made with the mouth closed but the infant fails to move air in and out of the lungs, bilateral choanal atresia (Chapter 368) or other obstruction of the upper respiratory tract should be suspected. The mouth should be opened, and the mouth and posterior of the pharynx cleared of secretions with gentle suction. An oropharyngeal airway should be inserted, and the source of the obstruction sought immediately. If effective respiratory flow is not produced by opening the infant’s mouth and clearing the airway, laryngoscopy is indicated. With obstructive malformations of the mandible, epiglottis, larynx, or trachea, an endotracheal tube should be inserted; prolonged endotracheal intubation or tracheostomy may be required. Respiratory failure caused by CNS depression or injury may require continuous mechanical ventilation.

Hypoplasia of the mandible (Pierre Robin, DiGeorge, and other syndromes; Chapters 300 and 303) with posterior displacement of the tongue may result in symptoms similar to those of choanal atresia and may be temporarily relieved by pulling the tongue or mandible forward or placing the infant in the prone position. A scaphoid abdomen suggests a diaphragmatic hernia or eventration, as does asymmetry in contour or movement of the chest or a shift of the apical impulse of the heart; these latter manifestations are also compatible with tension pneumothorax. A pneumothorax can be the presenting symptom in infants with pulmonary hypoplasia, renal malformations, or both.

Pulmonary causes of respiratory difficulty are discussed in Chapter 95.

Failure to Initiate or Sustain Respiration

Failure to initiate or sustain respiratory effort is common at birth. Infants with primary apnea respond to stimulation by establishing normal breathing. Infants with secondary apnea need ventilatory assistance. Secondary apnea usually originates in the CNS as a result of asphyxia or peripherally because of neuromuscular disorders. Prematurity alone is seldom a causative factor, except in infants weighing <1,500 g. Intrapulmonary problems, such as respiratory distress syndrome, pulmonary hypoplasia associated with oligohydramnios as in Potter syndrome or neuromuscular diseases, bilateral pleural effusions (hydrops fetalis), pneumothorax, and severe intrauterine pneumonia, may at times result in poor ventilation despite strong respiratory efforts. The lungs in affected infants may be noncompliant, and efforts to begin respirations may be inadequate to initiate sufficient ventilation.

Narcosis results from administration of morphine, meperidine, fentanyl, barbiturates, or tranquilizers to the mother shortly before delivery or from maternal anesthesia given during the 2nd stage of labor. This sequela should be avoided by the use of appropriate analgesic and anesthetic practices. Treatment includes initial physical stimulation and securing of a patent airway. If effective ventilation is not initiated, artificial breathing with a bag and mask must be instituted. At the same time, if the respiratory depression is due to an opiate, naloxone hydrochloride (Narcan), 0.1mg/kg, should be given intravenously or intramuscularly. Naloxone is contraindicated in infants born to mothers with opiate addiction because it precipitates acute neonatal withdrawal with severe seizures. If depression is due to other anesthetics or analgesics, artificial respiration should be continued until the infant is able to sustain ventilation. CNS-stimulant drugs should not be used because they are ineffective and may be harmful. External cardiac massage, correction of acidosis, and circulatory support with drugs may be important adjuncts to ventilation in the severely asphyxiated infant.

Neonatal Resuscitation

Although the majority of babies undergo a smooth physiologic transition and breathe effectively after delivery, 5-10% require active intervention to establish normal cardiorespiratory function. The goals of neonatal resuscitation are to prevent the morbidity and mortality associated with hypoxic-ischemic tissue (brain, heart, kidney) injury and to reestablish adequate spontaneous respiration and cardiac output. High-risk situations should be anticipated from the history of the pregnancy, labor, and delivery and identification of signs of fetal distress. Infants who are born limp, cyanotic, apneic, or pulseless require immediate resuscitation before assignment of the 1-min Apgar score. Rapid and appropriate resuscitative efforts improve the likelihood of preventing brain damage and achieving a successful outcome.

Guidelines for neonatal resuscitation propose an “integrated” assessment/response approach for the initial evaluation of an infant, consisting of simultaneous assessment of infant color, general appearance, and risk factors. The fundamental principles include evaluation of the airway, establishing effective respiration and adequate circulation; the guidelines also highlight the assessment and response to the neonatal heart rate and the management of infants with meconium-stained amniotic fluid.

Immediately after birth, an infant in need of resuscitation should be placed under a radiant heater and dried (to avoid hypothermia), positioned with the head down and slightly extended; the airway should be cleared by suctioning, and gentle tactile stimulation provided (slapping the foot, rubbing the back). Simultaneously, the infant’s color, heart rate, and respiratory effort should be assessed (Fig. 94-1).

Figure 94-1 Newborn resuscitation algorithm. CPAP, continuous positive airway pressure; ET, endotracheal; HR, heart rate; IV, intravenous; PPV, positive pressure ventilation.

(From Perlman JM, Wyllie J, Kattwinkel J, et al: Part 11: Neonatal resuscitation: 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science with Treatment Recommendations, Circulation 122:S517, 2010.)

The steps in neonatal resuscitation follow the ABCs: A, anticipate and establish a patent airway by suctioning and, if necessary, performing endotracheal intubation; B, initiate breathing by using tactile stimulation or positive-pressure ventilation with a bag and mask or through an endotracheal tube; C, maintain the circulation with chest compression and medications, if needed. Steps to follow for immediate neonatal evaluation and resuscitation are outlined in Figure 94-1 (Chapter 62).

If no respirations are noted or if the heart rate is <100 beats/min, positive pressure ventilation is given through a tightly fitted face bag and mask for 15-30 sec. In infants with severe respiratory depression that does not respond to positive-pressure ventilation via bag and mask, endotracheal intubation should be performed. Many authorities recommend early intubation for extremely low birthweight (ELBW) preterm infants. Guidelines for endotracheal tube size and depth of insertion in infants with different birthweights are shown in Table 94-1. If the heart rate does not improve after 30 sec with bag and mask (or endotracheal) ventilation and remains below 100 beats/min, ventilation is continued and chest compression should be initiated over the lower third of the sternum at a rate of 120 beats/min. The ratio of compressions to ventilation is 3:1. If the heart rate remains <60 beats/min despite effective compressions and ventilation, administration of epinephrine should be considered. Persistent bradycardia in neonates is usually due to hypoxia resulting from respiratory arrest and often responds rapidly to effective ventilation alone. Persistent bradycardia despite what appears to be adequate resuscitation suggests more severe cardiac compromise or inadequate ventilation technique. Poor response to ventilation may be due to a loosely fitted mask, poor positioning of the endotracheal tube, intraesophageal intubation, airway obstruction, insufficient pressure, pleural effusions, pneumothorax, excessive air in the stomach, asystole, hypovolemia, diaphragmatic hernia, or prolonged intrauterine asphyxia.

Traditionally, the inspired gas for neonatal resuscitation has been 100% oxygen. Resuscitation with room air (or 30%) is equally effective and may reduce the risk of hyperoxia, which is associated with decreased cerebral blood flow and generation of oxygen free radicals. Currently, 100% O₂ is recommended. Room air (or 30%) may become the preferred initial gas for neonatal resuscitation in the future; if the neonate does not achieve normal oxygen saturation levels within 90 sec, increasing concentrations of oxygen should be blended in (up to 100% oxygen) until normal oxygen saturation levels are achieved. If pulmonary hypertension is suspected (meconium aspiration, diaphragmatic hernia) one may consider 100% oxygen as the initial gas for resuscitation. Particular attention is required during the resuscitation of very LBW (VLBW) neonates, to monitor oxygen saturation so as to minimize the risk of hyperoxia.

Although the 1st breath normally requires pressures as low as 15-20 cm H₂O, pressures as high as 30-40 cm H₂O may be needed. Subsequent breaths are given at a rate of 40-60/min with a pressure of 15-20 cm H₂O. Noncompliant stiff lungs secondary to respiratory distress syndrome, congenital pneumonia, pulmonary hypoplasia, or meconium aspiration may require higher pressures. Successful ventilation is signified by adequate chest rise, symmetric breath sounds, improved pink color, heart rate >100 beats/min, spontaneous respirations, presence of end-tidal CO₂, and improved tone. Various devices to detect exhaled CO₂ and to confirm accurate placement of an endotracheal tube are available commercially. A laryngeal mask airway may be an effective tool to establish an airway, especially if bag and mask ventilation is ineffective or intubation is unsuccessful.

If the infant has respiratory depression and the mother has received an analgesic narcotic drug within 4 hr prior to delivery, naloxone hydrochloride (0.1 mg/kg) is given while adequate ventilation is maintained. Breathing in the depressed infant should be maintained until a response to naloxone is noted. Continuous observation of the infant is important because repeated doses of naloxone may be needed even after the infant has been transferred to the nursery owing to the short half-life of naloxone.

Medications are rarely required but should be administered when the heart rate is <60 beats/min after 30 sec of combined ventilation and chest compressions or during asystole. The umbilical vein can generally be readily cannulated and used for immediate administration of medications during neonatal resuscitation (Fig. 94-2). The endotracheal tube may be used for the administration of epinephrine if intravenous access is not available and/or for naloxone. Epinephrine (0.1-0.3 mL/kg of a 1:10,000 solution, given intravenously or intratracheally) is given for asystole or for failure to respond to 30 sec of combined resuscitation. The dose may be repeated every 3-5 min. Data in neonates are insufficient to recommend higher doses in infants who are unresponsive to the standard dose. Emergency volume expansion is accomplished with 10-20 mL/kg of an isotonic crystalloid solution or type O Rh-negative red blood cells (in acute hemorrhage). Volume infusions should be used cautiously during the resuscitation of a VLBW infant. Sodium bicarbonate (2 mEq/kg, 0.5 mEq/mL of a 4.2% solution) is often given and should be administered slowly (1 mEq/kg/min) if metabolic acidosis has been documented and the resuscitation is prolonged. Sodium bicarbonate should be given only after effective ventilation has been established, because such therapy may increase the blood CO₂ concentration and produce respiratory acidosis, complicating an existing metabolic acidosis. Restoration of oxygenation and tissue perfusion is the main treatment of metabolic acidosis associated with asphyxia.

Figure 94-2 Use of the umbilical vein for administration of medications during neonatal resuscitation.

(From Kattwinkel J, Bloom RS, editors: Neonatal resuscitation textbook, ed 5, Elk Grove, IL, 2006, American Academy of Pediatrics, American Heart Association.)

Severe asphyxia may also depress myocardial function and cause cardiogenic shock despite the recovery of heart and respiratory rates. Dopamine or dobutamine administered as a continuous infusion (5-20 µg/kg/min) and fluids should be started after the initial resuscitation effort, to improve cardiac output in an infant with poor peripheral perfusion, weak pulses, hypotension, tachycardia, and poor urine output. Epinephrine (0.1-1.0 µg/kg/min) may be indicated for infants in severe shock that does not respond to dopamine or dobutamine (Chapter 62).

Less severe degrees of poor cardiopulmonary transition in the delivery room can usually be managed by brief periods of bag and mask ventilation. Chest compression and medications are not needed for most neonates who have mild to moderate birth depression. Regardless of the severity of asphyxia or the response to resuscitation, asphyxiated infants should be monitored closely for signs of multiorgan hypoxic-ischemic tissue injury (see Table 93-1).

Meconium

Meconium staining of the amniotic fluid may be an indication of fetal stress; therefore, personnel skilled at endotracheal intubation and resuscitation should be present at the delivery. Previously the decision to intubate a neonate was based on the presence and thickness/consistency of the meconium-stained fluid; current evidence no longer supports this practice. If any meconium staining is present in the amniotic fluid, the obstetrician should suction the mouth, nose, and hypopharynx immediately after delivery of the head but before delivery of the shoulders. If the infant is vigorous with good respiratory effort and a heart rate >100 beats/min, tracheal intubation to aspirate meconium should not be attempted, and the mouth and nose should be suctioned with a bulb or suction catheter. If the infant is depressed with poor muscle tone and/or a heart rate <100 beats/min, tracheal intubation and suctioning should be performed. The endotracheal tube should be attached to a suction device, and free-flow oxygen should be provided throughout the procedure.

Shock

Circulatory insufficiency may be present at birth as a result of severe asphyxia or hemorrhage during gestation, labor, or delivery. Causes of blood loss include hemolysis; placental abruption or tear, placenta previa; traumatic injury to the umbilical cord or internal organs; and intracranial bleeding. Clinical manifestations include signs of respiratory distress, cyanosis, pallor, flaccidity, cold mottled skin, tachycardia or bradycardia, hepatosplenomegaly, and, rarely, convulsions. Edema and hepatosplenomegaly suggest hydrops fetalis or heart failure without shock. Shock from overwhelming infection may be present immediately after birth.

Supportive treatment with type O Rh-negative blood or normal saline is indicated for hemorrhage or hypovolemia, respectively. Oxygen should be administered and the metabolic acidosis corrected with sodium bicarbonate. A sympathomimetic agent such as dopamine or dobutamine may be needed to support cardiac output and blood pressure. The diagnosis and treatment of erythroblastosis fetalis are discussed in Chapter 97.2. If infection is present, appropriate antibiotics must be started as soon as possible.

After supportive measures have stabilized the infant’s condition, a specific diagnosis should be established, and appropriate continuing treatment instituted.

Pneumothorax

Infants may experience pneumothorax in the delivery room, resulting in respiratory distress and hypoxia. Approximately 1-2% of infants have pneumothorax after birth; only 0.05-0.07% have symptoms (Chapter 95.12). The risk is higher in infants requiring positive pressure ventilation or those with meconium-stained amniotic fluid. Rarely, an infant has a congenital malformation that results in lung hypoplasia, such as congenital diaphragmatic hernia or renal agenesis. Clinically, the infant demonstrates respiratory distress and has diminished breath sounds on the affected side. Transillumination may be helpful to confirm the diagnosis, particularly in the LBW infant. Emergency evacuation of a pneumothorax without radiographic confirmation is indicated in an infant who is unresponsive to resuscitation efforts, and has asymmetric breath sounds, bradycardia, and cyanosis. A 23-gauge butterfly needle or angiocatheter attached to a stopcock and syringe should be inserted perpendicular to the chest wall above the rib in the 4th intercostal space at the level of the nipple (Fig. 94-3). The air is evacuated. The catheter is then inserted with constant negative pressure, and the air evacuated.

Figure 94-3 Decompression of a pneumothorax.

(From Kattwinkel J, Bloom RS, editors: Neonatal resuscitation textbook, ed 5, Elk Grove, IL, 2006, American Academy of Pediatrics, American Heart Association.)

Airway Obstruction

Critical fetal and then neonatal airway obstruction represents an emergency in the delivery room. The ex utero intrapartum treatment procedure (EXIT procedure) allows time to secure the airway in an infant known to have airway obstruction for a variety of causes, including laryngeal atresia or stenosis, teratomas, hydromas, and oral tumors, before the infant is separated from the placenta. Uteroplacental gas exchange is maintained throughout the procedure. High-risk perinatal care has led to more frequent prenatal diagnosis of many disorders known to cause the critical high airway obstruction syndrome (CHAOS) (Fig. 94-4).

Figure 94-4 EXIT procedure. Baby with teratoma and critical high airway obstruction syndrome (CHAOS). Trachea is displaced to the lateral neck.

(Photograph compliments of Dr. Mark Wulkan, pediatric surgeon at Emory University.)

Abdominal Wall Defects

Appropriate management of patients with abdominal wall defects (omphalocele, gastroschisis) in the delivery room prevents excessive fluid loss and minimizes the risk for injury to the exposed viscera. Gastroschisis is the more common defect and typically the intestines are not covered by a membrane. The exposed intestines should be gently placed in a sterile clear plastic bag after delivery. A membrane often covers an omphalocele, and care should be taken to prevent its rupture. The infant should be transferred to a tertiary referral center for surgical consultation and evaluation for other associated anomalies (Chapter 99).

Injury During Delivery